1) Field of the Invention
The present invention refers to open end spinning, or rotor spinning. Open-end spinning machines generally consist of a plurality of individual spinning units, aligned on the two sides of the machine, each of which is made up of a spinning rotor, which produces twisted thread from singularised fibres of a rove, and a collection unit that—with the prior quality control of yarn with the interposition of a yarn clearer between the two components—carries the yarn to wind onto a quill to form a cone. This cone is thus formed pulling and winding the yarn on its surface, being pulled into rotation by the roller below on which the cone in formation is rested. The yarn is wound in a spiral on the cone in rotation since the collection unit is equipped with a thread-guiding device that distributes the yarn on the outer surface of the cone with to and fro axial motion.
The structure of the individual spinning station is illustrated in the scheme of FIG. 1, and its operation according to its normal running is briefly described hereafter.
Proceeding from the bottom towards the top, the single spinning station 1 consists of the actual spinning unit 2 and the collection unit 3, the main components of which that lead to the transformation of the rove of fibres made to run parallel in the cone of wound yarn are briefly illustrated hereafter.
The supply band or rove S is contained in a cylindrical vessel 4 where it is deposited in a double spiral. The rove S is supplied to the unit by a supply roller 5 passing through the funnel-shaped conveyor 6 and reaches the card 7, a rotating roller equipped with a toothed trimming that singularises the fibres of the rove S and conveys them by suction to the spinning rotor 8, which works in a vacuum.
In the spinning rotor 8, which rotates at very high speeds (up to 150,000 revs/minute and beyond), the singularised fibres are deposited in its peripheral throat by centrifugal effect; from here they are collected and picked up in the form of thread F, coming out axially from its central opening 9, receiving the twists from the rotation of the rotor itself in the path that runs between its inner throat and such an opening 9, thus generating the twisted thread F.
The pulling back of the thread is carried out with a pair of opposite extraction cylinders 11 and 12 for gripping the thread F and actuated at a controlled speed according to the arrow a, thus determining the linear production of yarn, generally indicated in m/min. The yarn clearer 14 for controlling the quality of the yarn F can be placed before the cylinders 11/12. The thread F thus produced enters into the collection unit 3, passes by a sensor 15 of the presence of thread and meets a compensator 16 for compensating the variations in length of the path between the spinning unit 2 and the deposit point of the yarn F on the cone. The thread-guiding device 21 distributes the thread on the cone in formation moving transversally with to and fro motion according to the double arrow b, actuated by a motor 20 that commands a longitudinal shaft 22 in common with the other units of the spinning machine.
The cone 25 collects the thread F and is held by the cone-holding arm 26 equipped with two idle tailstocks 27 that can be opened that go into engagement with the basic quill 28 of the cone. The cone in formation 25 is rested upon its actuation roller or collection cylinder 29.
2) Description of Related Art
Recently conceived automatic open-end spinning machines are equipped with service trolleys that patrol the sides of the spinning machine and carry out the required interventions stopping in front of the spinning unit that requires it.
The required interventions are essentially of three types:    for starting, at the beginning of the spinning from a still spinning machine, starting it and then placing a new quill in each station, carrying out the start-up with an auxiliary thread and winding the thread produced on the new quill to give a cone, after having eliminated that portion of auxiliary thread;    for reattachment, when the yarn is interrupted for whatever reason, without having yet reached the length foreseen for completing the cone, using the yarn already produced by the side of the cone, carrying out the reattachment and continuing the winding on the same cone. The reattachment procedure essentially consists of the opening, cleaning and closing of the rotor, the preparation of the tail of the rove, the capturing and preparation of the end at the side of the cone, the restarting of the rotor and the continuation of the supply, the re-introduction into the rotor of the prepared end, the re-extraction of the end connected to the newly produced thread winding it once again in the collection unit. The programmed cleaning cycle is the equivalent to the reattachment cycle, caused with a commanded breaking of the thread;    for lifting, after having reached the foreseen length for the cone to be complete. The finished cone is discharged and then one proceeds to starting the unit as outlined above.
Generally, such interventions are carried out by separating the cone 25 from its actuation cylinder 29, stopping its motion and actuating the cone 25 or its quill 28 by an auxiliary actuation roller arranged on-board the service trolley.
In the field of devices and procedures for the intervention of service trolleys on automated open end spinning machines the applicant is the owner, amongst others, of patents IT 1.146.694, EP 340.863, EP 443.220, EP 473.212, IT 1.258.220, IT 1.258.221, IT 1.258.222.
In general, the automation trolley consists of a structure mobile along the sides of the machine, a communication system with the central control unit of the spinning machine and with the spinning unit that make up the machine, a translation and stopping system of the trolley in front of the units that require intervention. The mobile structure carries on-board both its control unit and the members or groups of members dedicated to the single or multiple operations of the various cycles, which can at various times be required and which can be managed by said control unit. In open-end spinning machines that are currently available the automation trolley, faced with a failed reattachment or lifting cycle, repeats the operating sequence of the cycle from the beginning for a certain number of times, in general not more than three so as not to compromise the overall efficiency of the spinning machine.
The spinning unit, after said failed attempts of the trolley, is left out of order (with a red light) requiring the inspection of the operator who must identify the cause of the negative outcome of the automatic intervention and manually take steps to prepare it for a further intervention, again to be conducted automatically, but this time with a positive outcome.
With the evolution of open-end spinning machine technology, the range of counts, of yarns and of fibres to be worked has substantially widened, whereas the quality specifications of yarn have become more stringent. With the overall cycles relative to reattachment and lifting in which a substantial number of members or groups of members on-board the trolley cooperate, its efficiency, in other words, the successful completion of the operation without carrying out many attempts over and again, is very important. The coordination of said members is therefore very important for controlling them as regards relative positions, time and speed phasing of such members both in relation to each other and with respect to the thread that is adopted, manipulated and exchanged by said members, controlling the successful completion of each step of the process.